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Microbial leaching and chemical fixing joint repairing method for heavily polluted soil of chromium slag yard

A soil microorganism and chromium slag storage yard technology, which is applied in the field of remediation of contaminated soil in chromium slag storage yard, can solve the problem of unstable microbial Cr(VI) reduction efficiency, harsh soil conditions for electrodynamic remediation, and chromium slag storage yard pollution, etc. It can reduce the acid-base adjustment process, solve the problems of treatment and discharge, and solve the environmental risk problem.

Active Publication Date: 2015-04-29
CENT SOUTH UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these methods have their own limitations: the cost of immobilization / stabilization method is high, and the treatment effect is not good; the chemical reduction method is easy to cause secondary pollution of the soil, and how to remove Cr(VI) in the soil is the key Technical difficulties; the chemical cleaning method is only suitable for soils with a large permeability coefficient (such as sandy soil, etc.), and the introduction of cleaning fluid is easy to cause secondary pollution of the soil; the electrodynamic repair method has strict requirements on soil conditions and expensive repair costs
At present, the application and promotion of Cr(VI) reduction microbial remediation technology has encountered a bottleneck problem: affected by multiple factors in the soil environment, the microbial Cr(VI) reduction efficiency is unstable
[0004] At present, the chromium slag left by most chromium salt production enterprises in my country has been processed, but the chromium slag storage yard is seriously polluted, and the coexistence of slag and soil is common, and a single treatment method is difficult to meet the treatment requirements

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  • Microbial leaching and chemical fixing joint repairing method for heavily polluted soil of chromium slag yard
  • Microbial leaching and chemical fixing joint repairing method for heavily polluted soil of chromium slag yard

Examples

Experimental program
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Effect test

Embodiment 1

[0030] Example 1: Small-scale test effect of single strain and composite strain on the restoration of a chromium salt factory muck mixture in Changsha

[0031] At present, the pollution of chromium slag stockpiles in my country is complicated, and some single strains may have a good treatment effect on pure chromium-contaminated soil, but the treatment effect on chromium-contaminated slag-soil mixture is not so ideal, because chromium slag contains a part of acid-soluble For hexavalent chromium, the bacterial strain used for the remediation of chromium-contaminated soil is not necessarily suitable for the remediation of chromium slag, which is the case for the bacterial strain of the present invention. Moreover, the coexistence of dregs and soils is common in the upper soil of the dregs field, which leads to difficulties in treatment, and it is difficult for a single strain to meet the restoration requirements. Therefore, the present invention compares the remediation effects of...

Embodiment 2

[0036] Example 2: Remediation effect of high-concentration Cr(VI) contaminated slag from a chromium salt factory in Changsha, Hunan

[0037] Pick a single colony of Pannonibacter phragmitetus BB and Achromobacter sp.Ch-1 and inoculate it in a sterilized medium (3g yeast extract, 5g glucose, 3g sodium chloride, adjust pH=9.0-10.0 with 5mol / L NaOH; add water to 1L) Cultivate for 3 days to obtain a composite bacterial solution; inoculate 5% of the inoculum into a newly prepared non-sterile medium with 300mg / LCr(VI) added (pH value is 9.0-10.0), and culture at 28-32°C Until Cr(VI) is completely reduced, that is, culture until no hexavalent chromium is detected in the culture medium, and the concentration of bacteria is 3-5×10 9 CFU / mL. Then use the bacterial solution to continue to expand the culture in the same manner.

[0038] The former Changsha Chromium Salt Factory muck mixture is passed through a jaw crusher and a 1cm vibrating sieve, and the dregs are transferred into a 1...

Embodiment 3

[0041] Example 3 Remediation effect of slag contaminated by concentration Cr(VI) in a chromium salt factory in Changsha, Hunan

[0042] According to the same method as in Example 1, 25 tons of slag polluted by concentration Cr(VI) in a smelting waste slag yard of a certain chromium salt factory in Changsha was repaired.

[0043] After microbial spray repair, the contents of total chromium, water-soluble Cr(VI) and leached toxic Cr(VI) in the muck were reduced from 5533.5 mg / kg, 317.0 mg / kg and 34.5 mg / L to 3860.8 mg / L, respectively. kg, 27.4mg / kg and 3.7mg / L; after further chemical fixation with hydrazine hydrate, the leaching toxicity concentrations of water-soluble Cr(VI) and Cr(VI) in the slag soil were reduced to 1.74mg / kg and 0.35mg / L, respectively.

[0044] Table 2 Remediation effect of medium concentration Cr(VI) contaminated muck

[0045] Total Chromium (mg / kg) Water-soluble Cr(VI)(mg / kg) Leaching toxicity (mg / L) Raw muck 5533.5 317.0 34.5 ...

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Abstract

The invention discloses a microbial leaching and chemical fixing joint repairing method for heavily polluted soil of a chromium slag yard. The method comprises the following steps: spraying soil or muck of a chromium slag yard with a composite bacteria liquid which is obtained by cultivating compound strains Pannonibacter phragmitetus BB and Achromobacter sp.Ch<-1>; restoring Cr(VI) in the obtained leacheate into Cr(III), forming sediments in an alkaline condition, precipitating and recycling chromium; and carrying out chemical fixing on the Cr(VI) which is not leached from the soil or muck through hydrazine hydrate. By virtue of the method, the soil and muck with three different Cr(VI) pollution levels are repaired; the total removal rates on chromium are respectively 11.4%, 30.2% and 14.0%; the removal rates on water-soluble Cr(VI) are respectively 99.6%, 99.5% and 98.3%; and the leaching toxicity concentration of the Cr(VI) in the soil or muck is lower than 0.5mg / L.

Description

technical field [0001] The invention belongs to the field of environmental engineering, and in particular relates to a restoration method for soil polluted by chromium slag storage yards, in particular to a combined restoration method of microbial leaching and chemical fixation of heavily polluted soil in chromium slag storage yards of chromium salt production enterprises. Background technique [0002] In 2011, the State Council approved the "Twelfth Five-Year Plan" for Comprehensive Prevention and Control of Heavy Metal Pollution, marking the comprehensive development and implementation of heavy metal pollution prevention and control work across the country. In heavy metal pollution, Cr(VI) poses a great threat to the safety of humans, animals and plants due to its high toxicity, strong oxidative properties and high carcinogenicity. Cr(VI) mainly comes from chromium slag. About 600,000 tons of chromium slag are newly discharged every year in the country, and about 5.48 mill...

Claims

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Application Information

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IPC IPC(8): B09C1/08B09C1/10
Inventor 杨志辉柴立元王庆伟王洋洋廖映平高伟荣张志
Owner CENT SOUTH UNIV
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